University of Crete HEP Seminars


Holographic Chern–Simons defects

Speaker: Mitsutoshi Fujita
Institution: University of Kentucky
Time: Tuesday 18 October 2016, 14:00
Venue: 2nd floor seminar room
Abstract: We study SU(N) Yang–Mills–Chern–Simons theory in the presence of defects that shift the Chern–Simons level from a holographic point of view by embedding the system in string theory. The model is a D3–D7 system in Type IIB string theory, whose gravity dual is given by the AdS soliton background with probe D7-branes attaching to the AdS boundary along the defects. We holographically renormalize the free energy of the defect system with sources, from which we obtain the correlation functions for certain operators naturally associated to these defects. We find interesting phase transitions when the separation of the defects as well as the temperature are varied. We also discuss some implications for the Fractional Quantum Hall Effect and for two-dimensional QCD.

A universal theory for fluid dynamics with explicitly broken boost symmetries

Speaker: Jelle Hartong
Institution: The Niels Bohr Institute, Copenhagen University
Time: Tuesday 7 February 2017, 14:15
Venue: 2nd floor seminar room
Abstract: Theoretical investigations into the properties of strange metals suggest that these are described by effective field theories that are strongly coupled and that have non-relativistic scaling exponents. Such systems do not have boost invariance. In this talk I will discuss how to describe such theories in the hydrodynamic limit. More explicitly, I will first discuss an ideal gas of particles with dispersion relation w ~ k^z for any z. I will then describe the general thermodynamic properties of systems with no boost symmetries by introducing velocity as a chemical potential whose conjugate variable is momentum. I will then define perfect fluids and finally discuss first order corrections in the case of broken Galilean boost invariance.

Mixed Correlator 4D N=1 Superconformal Bootstrap

Speaker: Andreas Stergiou
Institution: CERN
Time: Tuesday 21 February 2017, 14:15
Venue: 2nd floor seminar room
Abstract: The numerical conformal bootstrap program has produced a wide range of impressive results concerning conformal field theories in various spacetime dimensions. In this talk I will focus on an application of this program to four-dimensional conformal theories with N=1 supersymmetry. In such theories a kink was found some time ago in the upper bound on the dimension of the first real scalar operator that appears in the operator product expansion of a chiral operator with its conjugate. Kinks signify isolated solutions to crossing equations, and are typically associated with specific conformal field theories. The nature of the putative theory at the N=1 kink remains mysterious. In this talk I will present numerical results concerning 4D N=1 theories using mixed correlation functions, and provide ample evidence that a special conformal field theory lives at the kink.